DE 199 44 927 A1 discloses a crane with a jib, which is supported by means of a counter jib and a counterweight carriage.
U.S. Pat. No. 3,398,967 discloses a crane with a leveling device. U.S. Pat. No. 4,275,902 dis-closes a crane with an auxiliary support. DE 10 2011 119 655 A1 discloses a crane with an additional support.